Location: Chemistry ResearchTitle: Reduced stomatal conductance in plants grown under elevated carbon dioxide leads to lower emission of herbivore induced volatiles.
|TUMLINSON, JAMES - Pennsylvania State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/17/2017
Publication Date: N/A
Technical Abstract: Terpene volatiles produced by sweet corn (Zea Mays) upon infestation with pests such as Beet armyworm (Spodoptera exigua) function as part of an indirect plant defense mechanism by attracting parasitoid wasps. To investigate the effect of climate change on this indirect defense, we determined the impact of elevated carbon dioxide (CO2) on herbivore induced volatile emission. We found that S. exigua infested sweet corn grown in 2 x ambient CO2 had decreased emission of its major sesquiterpene, beta-caryophyllene, and two homoterpenes, (3E)-4,8-dimethyl-1,3,7-nonatriene and (3E,7E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. A similar decrease in emitted volatiles was seen in response to treatment with the elicitor S. exigua regurgitant. Measurement of elicitor induced internal leaf volatiles showed no effect of elevated CO2 on homoterpene levels and an accumulation of beta-caryophyllene. Furthermore, gene expression analysis reveled that elevated CO2 resulted in a decrease of elicitor induced caryophyllene synthase (TPS23) expression. These data indicate that reduced emissions are likely due to reduced ability of the volatiles to exit the leaf resulting in their accumulation and suppression of their biosynthesis. Given the well established effect of elevated CO2 in reducing stomatal conductance, that we also observe, and the fact that the exit route of leaf volatiles is via the stomata, our data point to CO2 mediated stomatal closure as a primary factor in reduced emission of herbivore induced volatiles under elevated CO2. Extrapolation of these findings lead to the conclusion that elevated CO2 will likely result in a compromised ability of plants to utilize volatiles for indirect defense.